The invention relates to a cage for a ball joint, the cage being configured essentially annular about a longitudinal axis, said cage having an inner surface and an outer surface, two edges delimiting the inner surface and the outer surface, and at least one window, wherein the inner surface surrounds an inner space of the cage and two webs laterally adjoin the at least one window. The invention also relates to a ball joint.
Ball joints are used, for example, in drive trains of vehicles in order to transmit the torque of the engine to a wheel axle. The balls serve for force or torque transmission between an outer hub and an inner hub of the joint and a cage having windows holds the balls in a plane in order to permit bending of the joint.
Various embodiments of ball cages are known from the prior art. German unexamined application no. DE 1 202 588 discloses a sprung cage, the windows of which are each provided with a slit. A cage with windows of different lengths is described in U.S. Pat. No. 7,393,284 (=DE 103 04 156). A cage with windows, the sides of which have a pointed shape, is disclosed in German patent no. DE 43 29 769 C1. German patent no. DE 28 16 255 discloses a cage, the outer surface of which has a bevel which extends from the edge of the cage to a longitudinal side of a window. Mounting enlargements are provided between the windows of the cage disclosed in published Australian patent application no. AU 2002-352039 A1 (=WO 03/046397). U.S. Pat. No. 6,461,244 (=DE 102 01 169) discloses a cage which has a groove for reducing the periphery of the cage provided between two windows. A cage, the windows of which each accommodate two balls adjoining one another, is disclosed in U.S. Pat. No. 7,648,418 (=DE 103 37 918). US patent publication No. U.S. 2007/0298167 (=DE 10 2006 020 711) discloses a cage which is configured such that lateral edges of the windows have a greater wall thickness than the remainder of the cage. U.S. Pat. No. 6,241,615 (=DE 198 31 011) discloses a cage, the windows of which have reinforcing projections. U.S. Pat. No. 4,846,764 (=DE 38 30 579) describes a cage produced from two half cages made of sheet metal.
A problem of the prior art cages lies in the fact that the balls press against the borders of the windows and that, due to the high torques and relative movements or sliding movements of the balls and the high temperatures resulting therefrom, damage can be caused to the cages, particularly in the region of the window support surfaces. A solution belonging to the prior art consists in increasing the wall thicknesses of the windows. This is undertaken selectively, only in the region of the windows, in order not to increase the weight of the cages unnecessarily. However, the associated production method is complex and costly. In particular, it is mostly metal-removing methods that must be used which, due to the interrupted structures of the material, further reduce the strength of the cage.